Inhibrx Biosciences is vying for approval of its targeted therapy, ozekibart, in chondrosarcoma.
This follows the positive outcome of the Phase II ChonDRAgon trial (NCT04950075), which found that ozekibart could cut a patient’s risk of disease progression or death by 52% compared with placebo.
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Investors appear to be enthusiastic about ozekibart’s market potential, as the company’s stock soared 61% upon the results debut, rising from $28.36 at market close on 23 October to $49.12 pre-market on 24 October (6am ET) after the positive results debuted.
In the registrational study, the death receptor 5 (DR5)-targeting antibody met its primary endpoint, offering significant improvements to progression-free survival (PFS) over placebo.
Following treatment with ozekibart, patients’ median PFS was more than double that of the placebo group, with the therapy group experiencing a 5.52-month PFS as opposed to the 2.66 months seen in the placebo cohort.
These benefits were seen across all chondrosarcoma subgroups, including isocitrate dehydrogenase (IDH)-wild-type and mutant patients. This finding could be notable, as some research suggests that IDH-mutant disease is associated with poorer outcomes. However, this is a point of contention among the scientific community.
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By GlobalDataDespite promising efficacy, ozekibart, which was previously known as INBRX-109, led to a patient death, which was caused by liver toxicity. However, Inhibrx Biosciences noted that this occurred “before the implementation of mitigation measures”, and that hepatoxicity was only observed in those with underlying liver function issues.
When hepatotoxicity was accounted for, the drug resulted in a low incidence of mild-to-moderate treatment-related hepatic adverse events, which occurred at a rate of 11.8% compared with the 4.5% seen in the placebo arm.
Following the promising results of the registrational ChonDRAgon study, Inhibrx Biosciences plans to submit a biologics licence application (BLA) to the US Food and Drug Administration (FDA) for ozekibart in chondrosarcoma by Q2 2026. If approved, the drug could become the first targeted therapy to make it to market in this indication.
This trial outcome makes ozekibart the first therapy to demonstrate a statistically significant PFS benefit in a chondrosarcoma clinical trial.
This will be welcome news for patients with the disease, as there are currently no targeted therapies approved for use in the indication, which has been notoriously difficult to treat due to its lack of response to conventional chemotherapies.
Inhibrx Biosciences retained the rights for ozekibart in 2024 following Sanofi’s $1.7bn acquisition of its parent corporation, Inhibrx.
If ozekibart makes it to market, it could face competition from Servier Pharmaceuticals’ IDH inhibitor, Tibsovo (ivosidenib), which is currently in Phase III for conventional chondrosarcoma.
Bristol Myers Squibb’s blockbuster programmed cell death protein 1 (PD-1) blocker, Opdivo (nivolumab), could also make a debut on the chondrosarcoma market down the line, following the positive results of the Phase II IMMUNOSARC I (NCT03277924) master trial. This study found that Opdivo plus Sutent (sunitinib) has activity in advanced extraskeletal myxoid chondrosarcoma.
Ozekibart shows triple threat potential
While chondrosarcoma was Inhibrx Biosciences’ original focus for ozekibart, the biotech is now exploring the drug in other indications, including heavily pretreated colorectal cancer. In an early-stage trial, the drug triggered an overall response rate (ORR) of 23% while demonstrating disease control in 92% of patients when used alongside combination chemotherapy, FOLFRI.
Meanwhile, the drug also showed promise in relapsed/refractory Ewing sarcoma, demonstrating an ORR of 64% and a DCR of 92%.
In a 24 October statement, Inhibrx Biosciences CEO and co-founder Mark Lappe noted that the results could signal ozekibart’s potential “not only in sarcomas, but also in high unmet need solid tumour indications”.
